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Anyone want to comment on these schematics? Anything stand out as being horribly broken? The plan is to have a Z280 in 16-bit ZBUS mode. An Altera CPLD acts as a 'chipset' to handle DRAM, PS/2 keyboard port, and signals for the 8-bit ISA slots. A 74373 latches/buffers some address lines. 74245...

I have a detailed manual pertaining to an ARM7TDMI CPU, which I believe suports the "ARM4" instruction set. I don't by any means have a solid grasp of what the differences are between each generation of instruction set or each generation of hardware architecture, or which corresponds to which...

I'm trying to use PIT counter 0 for timing in a (protected mode) DOS program. (I also have RDTSC as an option but it is not available on 486/5x86.) Simply reading port $40 two times, and using only the second (high) byte to do my thing seemed to work fine inside NTVDM on my "modern" dual-core...

Is it possible to open a TCP port on localhost (port 6000?) and send X11 protocol commands to implement a GUI application on a Linux system? Or is that not how things are done? It sounds like the 'normal' way to interface with X would be through libX11 but can that abstraction layer be cut out...

I have custom fonts disabled in my browser to conserve bandwidth, but many websites are using invalid 'private' unicode characters that correspond only to something in their custom font. These render then as a box with a hex code in it or some random Chinese character. Does anyone know if there...

I know there were some 5V chips that could officially also run on 3.3V, generally with a lower speed. Examples would be NEC V810 or Hitachi SH2, according to their respective datasheets. I'm wondering if this might be true of any DRAM, SRAM, or (E)EPROMs. So far I haven't seen any datasheets...

I heard that the number of clock cycles for a multiply varies depending on the number of '1' bits in one of the operands (ie. multiplication is a microcoded shift-and-maybe-add loop). But does anyone know which operand it is? MOVE #127,d0 MULU #2,d0 MOVE #2,d0 MULU #127,d0 Which is faster on...

Older browsers are being blocked by many sites by way of TLS requirements. Annoying to say the least. So why not a proxy that intercepts the browser request and then fetches the document on its behalf, using whatever secret handshakes are necessary? This is what I have done using CURL 7.53.1 as...

I am trying to verify IRQ operation on an 8-bit bus card in my PC AT. I designed a card with a YM2203 fm synthesizer that includes a timer interrupt. The card has some problems that I would like to take care of in a second design, but before I do that I want to demonstrate that the timer...

After doing a couple basic PCB designs using KiCad, I was thinking about taking on some more complex projects. Of course I would like to avoid assembling a huge board with a sea of TTL chips (or having to buy all those chips) as was done in the old days. So I started looking into CPLDs. It turns...

Hi, just registered on this forum. My first machine was an Atari 800XL, from which I moved to x86 PCs. But I also fooled with Amiga and MSX, and to a lesser extent C64 and Apple, at a time when these things were merely old and not rare collectors items like they seem to be today. In the past I...